Could Gut be the Origin of Parkinson's Disease?

Highlights

• Many gastrointestinal problems such as constipation can start decades before manifestation of Parkinson's disease.
• Vagal nerve may be responsible for conducting Parkinson's disease from the gut to the brain.
• Resection or removal of a part (selective) or whole (truncal) of the vagal nerve, reduced the incidence of Parkinson's disease.

Parkinson's disease may originate in the gut and spread to the brain via the vagus nerve. The vagus nerve is the 10th cranial nerve that has both sensory and motor functions. It extends from the brainstem to the abdomen. It is responsible for controlling involuntary body processes like heart rate and food digestion.

For the study, people who had undergone resection surgery or the removal of the main trunk or branches of the vagus nerve, were examined.

This surgery called vagotomy is used for people with ulcers. There are two types of vagotomy:

• Truncal- in this type, the entire vagal nerve, both anterior and posterior sections, is removed. It curbs acid secretion and promotes ulcer healing.
• Selective- only certain branches of the vagal nerve are removed.

Researchers compared 9,430 people who had a vagotomy over a 40-year period to 377,200 people from the general population, who served as the controls, from the national registers in Sweden.

During this period, Parkinson's manifested in 101 people or 1.07% who had a vagotomy, compared to 4,829 people or 1.28% in the control group.

When these people were followed for a 5 year period, it showed that those who had truncal vagotomy were less likely to develop Parkinson's disease compared to the control group. Parkinson's developed in 19 people or 0.78% who had truncal vagotomy compared to 3,932 people or 1.15% who did not have surgery.

Selective vagotomy caused Parkinson's in 60 people or 1.08%, in a 5 year period. This shows that truncal vagotomy lowered the incidence of Parkinson's compared to selective vagotomy.

Advertisement

The results showed people who underwent truncal vagotomy at least five years before were 40% less likely to develop Parkinson's disease than those who had not undergone the surgery and had been followed for at least five years.

"These results provide preliminary evidence that Parkinson's disease may start in the gut," said study author Bojing Liu, MSc, of the Karolinska Instituet in Stockholm, Sweden. "Other evidence for this hypothesis is that people with Parkinson's disease often have gastrointestinal problems such as constipation, that can start decades before they develop the disease."

Advertisement

"In addition, other studies have shown that people who will later develop Parkinson's disease have a protein believed to play a key role in Parkinson's disease in their gut." Liu added. Misfolding of these proteins can spread this error fro cell to cell.

"Much more research is needed to test this theory and to help us understand the role this may play in the development of Parkinson's," Liu said. Additionally, since Parkinson's is a syndrome, there may be multiple causes and pathways.

One major limitation of the study was that certain subgroups had smaller number of participants. Though many confounding factors like chronic obstructive pulmonary disease, diabetes and arthritis were adjusted for, other potential factors like smoking, coffee drinking or genetics, that could affect the risk of Parkinson's disease, could not be controlled.

The study is published in the online issue of Neurology, the medical journal of the American Academy of Neurology.

References

1. different types of vagotomy procedure - (http://www.gpnotebook.co.uk/simplepage.cfm?ID=67502107&linkID=35019&cook=no&mentor=1)
2. THE VAGUS NERVE (CN X) - (http://teachmeanatomy.info/head/cranial-nerves/vagus-nerve-cn-x/)
3. Bojing Liu et al. Vagotomy and Parkinson disease. Neurology; (2017) doi.​org/​10.​1212/​WNL.​0000000000003961

Source-Medindia